1. Field of the Invention
The present invention relates to a throttle valve control apparatus for controlling a flow amount of intake air of an internal combustion engine and a motor vehicle.
2. Description of the Prior Art
An electrical control type throttle apparatus opening and closing a throttle valve of an internal combustion engine by a motor-driven actuator (for example, a direct current motor, a stepping motor, a torque motor and a brushless motor) is put into practice.
The electrical control type throttle apparatus is structured such as to control an optimum throttle valve angle (throttle valve opening degree) corresponding to an engine state on the basis of an opening degree signal of an accelerator pedal and a traction control signal. For this purpose, a sensor for detecting an angle of the throttle valve, so-called a throttle sensor (which may be sometimes called as an opening degree meter or a throttle position sensor) is attached to a throttle body.
A potentiometer system is generally employed in the throttle sensor, and a brush (a sliding element) rotating together with a throttle valve shaft slides on a resisting body, thereby outputting a potential difference signal (a sensor detecting signal) corresponding to a throttle valve opening degree (for example, refer to Japanese Unexamined Patent Publication No. 9-32588).
This kind of conventionally used throttle sensor is structured such that the brush is in contact with a variable resistance and a conductor formed on a resistance base plate so as to slide thereon. Accordingly, a service life of the sensor is short and the sensor is frequently in trouble. A double route of sensor is employed so as to detect a trouble of sensor and mutually back up, however, this can not basically solve the problem.
Further, since the trouble mentioned above is generated in the conventional motor vehicle at a high possibility, and a control parameter is controlled by an output of the sensor having a short service life, an accuracy for operating and controlling the internal combustion engine is low.
There has been known Japanese Patent No. 2845884 as a structure for detecting the opening degree of the throttle valve in a non-contact manner.